home-assistant.io/source/_components/light.mqtt_json.markdown

layout	title	description	date	sidebar	comments	sharing	footer	logo	ha_category	ha_iot_class	ha_release
page	MQTT JSON Light	Instructions for how to setup MQTT JSON lights within Home Assistant.	2016-08-09 08:30	true	false	true	true	mqtt.png	Light	depends	0.26

The mqtt_json light platform lets you control a MQTT-enabled light that can receive JSON messages.

This platform supports on/off, brightness, RGB colors, XY colors, color temperature, transitions, short/long flashing and white values. The messages sent to/from the lights look similar to this, omitting fields when they aren't needed:

{
  "brightness": 255,
  "color_temp": 155,
  "color": {
    "r": 255,
    "g": 255,
    "b": 255,
    "x": 0.123,
    "y": 0.123
  },
  "effect": "colorloop",
  "state": "ON",
  "transition": 2,
  "white_value": 150
}

In an ideal scenario, the MQTT device will have a state topic to publish state changes. If these messages are published with the RETAIN flag, the MQTT light will receive an instant state update after subscription and will start with the correct state. Otherwise, the initial state of the light will be off.

When a state topic is not available, the light will work in optimistic mode. In this mode, the light will immediately change state after every command. Otherwise, the light will wait for state confirmation from the device (message from state_topic).

Optimistic mode can be forced, even if state topic is available. Try enabling it if the light is operating incorrectly.

# Example configuration.yaml entry
light:
  - platform: mqtt_json
    command_topic: "home/rgb1/set"

{% configuration %} name: description: The name of the light. required: false type: string default: MQTT JSON Light command_topic: description: The MQTT topic to publish commands to change the light’s state. required: true type: string brightness: description: Flag that defines if the light supports brightness. required: false type: boolean default: false brightness_scale: description: "Defines the maximum brightness value (i.e. 100%) of the MQTT device." required: false type: integer default: 255 color_temp: description: Flag that defines if the light supports color temperature. required: false type: boolean default: false effect: description: Flag that defines if the light supports effects. required: false type: boolean default: false effect_list: description: The list of effects the light supports. required: false type: string list flash_time_long: description: The duration, in seconds, of a “long” flash. required: false type: integer default: 10 flash_time_short: description: The duration, in seconds, of a “short” flash. required: false type: integer default: 2 optimistic: description: Flag that defines if the light works in optimistic mode. required: false type: boolean default: "true if no state topic defined, else false." qos: description: The maximum QoS level of the state topic. required: false type: integer default: 0 retain: description: If the published message should have the retain flag on or not. required: false type: boolean default: false rgb: description: Flag that defines if the light supports RGB colors. required: false type: boolean default: false state_topic: description: The MQTT topic subscribed to receive state updates. required: false type: string white_value: description: Flag that defines if the light supports white values. required: false type: boolean default: false xy: description: Flag that defines if the light supports XY colors. required: false type: boolean default: false availability_topic: description: The MQTT topic subscribed to receive availability (online/offline) updates. required: false type: string payload_available: description: The payload that represents the available state. required: false type: string default: online payload_not_available: description: The payload that represents the unavailable state. required: false type: string default: offline {% endconfiguration %}

Make sure that your topics match exact. `some-topic/` and `some-topic` are different topics.

XY and RGB can not be used at the same time. If both are provided, XY overrides RGB.

{% linkable_title Comparison of light MQTT platforms %}

Function	mqtt	mqtt_json	mqtt_template
Brightness	✔	✔	✔
Color temperature	✔	✔	✔
Effects	✔	✔	✔
Flashing	✘	✔	✔
RGB Color	✔	✔	✔
Transitions	✘	✔	✔
XY Color	✔	✔	✘
White Value	✔	✔	✔

{% linkable_title Examples %}

In this section you find some real life examples of how to use this sensor.

{% linkable_title Brightness and RGB support %}

To enable a light with brightness and RGB support in your installation, add the following to your configuration.yaml file:

# Example configuration.yaml entry
light:
  - platform: mqtt_json
    name: mqtt_json_light_1
    state_topic: "home/rgb1"
    command_topic: "home/rgb1/set"
    brightness: true
    rgb: true

{% linkable_title Brightness and no RGB support %}

To enable a light with brightness (but no color support) in your installation, add the following to your configuration.yaml file:

# Example configuration.yaml entry
light:
  - platform: mqtt_json
    name: mqtt_json_light_1
    state_topic: "home/rgb1"
    command_topic: "home/rgb1/set"
    brightness: true

{% linkable_title Brightness Scaled %}

To enable a light using a brightness scale other than 8bit the brightness_scale option may be added to denote the "fully on" value:

# Example configuration.yaml entry
light:
  - platform: mqtt_json
    name: mqtt_json_light_1
    state_topic: "home/light"
    command_topic: "home/light/set"
    brightness: true
    brightness_scale: 4095

Home Assistant will then convert its 8bit value in the message to and from the device:

{
  "brightness": 4095,
  "state": "ON",
}

{% linkable_title Implementations %}

• A full example of custom lighting using this platform and an ESP8266 microcontroller can be found here. It supports on/off, brightness, transitions, RGB colors, and flashing.

• There is also another implementation forked from the above repo, it supports all the same features but is made for addressable LED strips using FastLED on a NodeMCU V3 it can be found here.

• MQTT JSON Light is another implementation for ESP8266 including MQTT discovery.

• esphomelib is a library for ESP32-based boards that has many of Home Assistant's MQTT features (like discovery) pre-implemented and provides high-level abstractions for components such as lights or sensors.